Conventional gripping devices for revolving tools are used to grip various revolving tools, such as aiguilles, reamers, screw taps and so on, and are also called as chuck. A typical chuck such as a drill chuck includes a drill body, plural jaws (e.g. three jaws), a nut, a sleeve etc., as well as a rear sleeve in certain cases. In addition, a bearing assembly may be included in a chuck in order to reduce friction. The plural jaws are mounted in plural inclined holes of the drill body with the inclined holes equally arranged in the drill body. The nut, provided in a nut groove of the drill body, cooperates with the thread of the jaws to form a thread transmission mechanism. The outer sleeve is fitted around the nut (and in some instances, a nut sleeve is fitted around the nut). The outer sleeve has keys thereon while the nut has key grooves corresponding to said keys thereon, such that the outer sleeve can be coupled with the nut sleeve (the nut) via the keys.
In operation, the outer sleeve can be rotated manually and sequentially drive the nut sleeve and/or nut. Afterward, the nut drives the jaws to move in the inclined holes of the drill body back and forth so as to urge the three jaws to open or close in order to release or grip tools.
Since a drill chuck is generally operated under the operating condition of vibration and impact, the nut tends to loosen due to inertia, making the jaws release a tool handle. Therefore, in operation, the nut needs to be repeatedly fastened for many times, which brings about an obstacle in production.